Until now, it is known that fumes generated during producing charcoal are separated into three layers within a container when cooled for the production of wood vinegar (pyroligneous acid) tar. That is, generated fumes are separated into three layers: (a) wood vinegar (aqueous), (b) tar and wood vinegar, and (c) tar (semisolid) from top to bottom within a container, since the wood vinegar is aqueous and the tar is not soluble in water and has a high specific gravity. The fraction (b) described above, in particular, is a mixture of tar and wood vinegar, and it is difficult to separate them completely.
In addition, tar is of oil, and does not result in complete dryness. For example, experiments in which tar was applied to plates with given dimensions, followed by allowing the plates to be placed in a dryer at about 60° C. for 60 days gave results from which it turned out that the tar was not dried completely and remained in a tacky (sticky) state at all times.
In order to avoid this disadvantage of incomplete drying of tar, attempts are possibly be made to dilute tar in a volatile solvent such as a lacquer thinner, alcohol, benzine, petroleum, or the like, followed by application of this diluted tar. In this case, however, the tar will remain in a tacky state and its complete dryness will be not achieved, as in the above-described experiments, after the solvent vaporizes.
As mentioned above, tar is not soluble in water and does not exist in a stable state in a liquid, and precipitation of tar components is caused, for example, during production and storage, thereby leading to disadvantage of separation into wood vinegar and tar. In addition, tar is not dried completely, and thus there is a disadvantage of causing it to remain in a sticky, tacky state in the case of applying it to plates and others.
Tar, on the other hand, has been known in the past to have rot-proofing and termite-controlling effects. Therefore, it can be expected that if tar is used as coatings to apply tar to lumbers and others, rot, damages by termites, and others can be prevented. Additionally, tar does not make human bodies and the environment dirty and has extremely high usefulness.
However, tar is not dissolved in a liquid in a stable state, and thus it is difficult to mix tar into coating compositions. Even if tar is applied to lumbers and others, the tar is not dried completely, and thus there are problems of precluding its use as coating compositions, due to attaching of tar in surrounding areas.
Therefore, the first object of the present invention is to provide an aqueous solution in which tar is dissolved in a stable state.
The second object of the present invention is to provide a tar-containing coating composition having highly rot-proofing and termite-controlling effects in which tar can be completely dried after being applied for coating.